Bug: Media Encoder 2026 renders dark/black left edge on MXF OP1a exports (vertical video with blur)

Hello,

Since updating to Media Encoder 2026, I have encountered an issue when exporting vertical videos (using a blurred background layer to fill the 16:9 frame) to MXF OP1a.

The exported video results in a black or very dark artifact/edge on the left side of the frame.

Additional Details:

• This issue does not occur when exporting directly from Premiere Pro using the exact same project settings.

• This issue did not happen in Media Encoder 2025 using the same sequence settings, project files, and export presets.

• Disabling "Enable Smart Rendering codec" in the export settings does not resolve the problem.

Could the team please look into how the 2026 version handles color management or rendering on MXF OP1a containers for vertical compositions?

Thank you!